Pressure differential pumps

ABSTRACT

Embodiments of the present disclosure relate generally to pumps and systems that use a differential pressure gradient to transfer fluids. In one example, the pumps may use available differential pressure that exists due to outside pressure and cabin pressure due to altitude on-board a vehicle such as an aircraft.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/879,872, filed Sep. 19, 2013, titled “Pressure Differential Pump,” the entire contents of which are hereby incorporated by reference.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure relate generally to pumps and systems that use a differential pressure gradient to transfer fluids. In one example, the pumps may use available differential pressure that exists due to outside pressure and cabin pressure due to altitude on-board a vehicle such as an aircraft. In other examples, the pumps may use a created differential pressure, such as that created by a vacuum generator pump on any vehicle. The pumps and systems may be designed to transport any type of fluids, non-limiting examples including fluids that may contain suspended solids, such as black or grey water, anti-freeze, or any other fluids.

BACKGROUND

Often aboard passenger transportation vehicles, there exist high or low pressure systems as a consequence of propulsion or environmental conditions. For example, an aircraft in flight may experience a pressure differential that is created between the atmosphere outside the aircraft at an altitude and the internal pressurized cabin atmosphere. These high or low pressure systems represent useful differential pressure gradients that can be used to drive certain mechanical processes.

BRIEF SUMMARY

Embodiments described herein provide a pump system configured to use differential pressure. The pump system may generally include a pump body comprising at least one vacuum inlet, at least one fluid inlet, an outlet, a vacuum control member, and a reservoir configured for containing a fluid. There may be at least one piston housed within the pump body, the piston configured to move in response to pressure differential. The piston may include a spring body or any other tension-compression storing system that can be compressed when subjected to vacuum and that expands when the pump body is vented to ambient pressure. It is also possible for the pump to work such that a difference in pressure forces a hydraulic cylinder to move across the pump body, forcing movement of fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of one embodiment of a pump system that uses differential pressure to move fluids.

FIG. 2 shows a side exploded view of a piston that may be contained within a pump body.

FIG. 3 shows a perspective view of the piston components of FIG. 2.

FIG. 4 shows a side cut-away view of a pump body with a vacuum applied to compress piston components or to otherwise force the pistons open to create a reservoir space in the pump body.

FIG. 5 shows a side cut-away view of FIG. 4 with the pistons expanded to force fluid out of the reservoir.

FIG. 6 shows a schematic of a pump using a hydraulic cylinder to force fluid out of the reservoir.

FIG. 7 shows a cross-sectional view of a pump body having internal rails for guiding a piston.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide pumps designed to work based on differential pressure. The potential energy represented by differential pressure is particularly attractive in passenger transport vehicles, due to limitations on size, weight, and electrical energy inputs for various components. The present inventors thus determined that it would be beneficial to design pump devices that can use this energy source. Due to the inherent movement of passenger transportation vehicles as well as necessary size and weight restrictions for components to be used on such vehicles, on-board mechanisms are desirably small, lightweight, reliable, and able to function in a range of temperatures and environments. The pressure-differential pumps (PDP) described herein are devices that use the various pressure regimes available on-board a passenger transportation vehicle to drive fluids from one location to another.

FIG. 1 shows one example of a pressure differential pump (PDP) system 10. This system includes a pump body 12. The pump body 12 may be made up of two body components 14, 16. However, although two body components 14, 16 are shown in FIG. 1, it should be understood that the body components 14, 16 may be integrally molded. It should also be understood that the pump body may be formed as a single integral body. Alternatively, there may be more than two body components provided to form the pump body 12. In the specific embodiment shown in FIG. 1, the body components 14, 16 may be formed as pinch valves. The general concept is that the pump body 12 has a reservoir 18 that can contain a fluid, and the pump body can move the contained fluid. The pump body 12 may receive a first applied pressure, and may use that pressure to move contained fluid toward an area having a different pressure. By using different pressure gradients, the system 10 can move fluids without using a high amount of power.

In one example, the pump body 12 forms a reservoir 18. The reservoir 18 may generally include one or more seals to prevent air and liquid leakages. The reservoir may be in fluid communication with an outlet 20. The outlet 20 is an exit point for the contained fluid to leave the pump body 12. In a specific embodiment, there may be more than one fluid outlet 20 provided. The pump body 12 also has at least one fluid inlet 22. The at least one fluid inlet 22 allows any type of fluid to be received into the reservoir 18 of the pump body 12. In a specific embodiment, there may be more than one fluid inlet 22 provided. In FIGS. 1 and 4, a pump inlet 22 is positioned on an outer surface of the pump body (leading to the reservoir 18). A pump outlet 20 is positioned generally opposite the inlet 22 on outer surface of the pump body 12 (leading away from the reservoir 18).

Fluid may be delivered into the pump body reservoir 18 using any appropriate manner. In one example, the fluid may be forced into the reservoir 18 from another system. The fluid may be grey water from a sink basin that flows into the pump body 12. The fluid may be potable water delivered from an on-board water tank. The fluid may be anti-freeze to be delivered to one or more aircraft components. The fluid may be grey water that has been filtered, collected, and reserved from a sink for delivery to a toilet for flushing purposes. The type of fluid to be moved via a pump system 10 is not intended to be a limiting factor of the pump structures described. In another example, the volume of the pump reservoir 18 may collect fluids (from any source) drawn in by the vacuum-driven retreating action of one or more pistons 26, described further below. An inlet check valve (A) may allow fluids to be pulled into the pump through the fluid inlet 22, but prevent them from flowing backwards through the system during compression. Similarly, an outlet check valve (B) may allow fluids to pass through the outlet 20 (toward the pumping destination) during compression without allowing high pressure, downstream fluids to flow backward.

For example, as shown in FIG. 2, a piston system may be used to move water through the pump body 12. This example may include at least one tension-compression element that may be housed within the pump body 12. In one embodiment, the piston may include a compressible feature, such as a tension-compression element spring body 28, and a head 30. The piston head 30 may be attached to a yoke 50, with the spring body 28 positioned within. The yoke 50 may be a sliding yoke that helps create movement of the piston. The yoke 50 may also feature a sleeve 32, such as an elastomeric sleeve 32, around its circumference. The sleeve 32 may slide with the yoke 50 and help reduce or alleviate friction between the yoke 50 and the pump body 12 interior.

In an alternate embodiment, the piston may comprise a compressible substance, such as gas, that can force movement of the piston head 30. In any event, the piston is generally compressed when the pump body is open to vacuum, but expanded when the pump body is open to vent or ambient pressure. As shown in FIG. 3, the spring body 28 can be received in the yoke 50, which is received in the pump body 12 in use. In one example, the spring body 28 of the piston may have a normally-extended resting state. This is illustrated in FIGS. 2 and 3. As shown in FIG. 4, a second piston 34 (with related components) may be positioned in the pump body 12 as well. The pistons 26, 34 may be positioned on opposing sides of the pump body 12, such that when retracted, they help define the reservoir 18.

In one example, the piston(s) may be formed of yoke 50 that is configured as a hollow cylinder suspended within an elastomeric sleeve 32. Differential pressure may be applied to a sealed region behind the yoke/cylinder barrel. One or more tension/compression-storage components 28 may be located within this sealed region. In one embodiment, the tension-storage component may be a spring. The elastomeric sleeve 32 may act to atmospherically isolate the interior of the region behind the cylinder by bending or folding, while maintaining a seal, without sliding past itself or other components. This design can allow for reduced friction motion by eliminating a sealing component such as an o-ring. (However, it should be understood that an o-ring may be used instead or additionally.) This design can also allow the compression of the piston 26 via pressure differential benefit, while ensuring that remaining pump components remain isolated from the pumped fluids. This contributes to the overall reliability of the system over existing pump architectures. In one example, a low-friction sleeve 32 may be attached to a piston head 30 and piston yoke 50.

In another embodiment, piston guidance may be maintained via one or more internal rails 48 instead of (or in addition to) an o-ring-containing piston or a sleeve 32. The internal rails 48 may assist with assembly of the pump body components. The internal rails 48 may also help keep the piston from rotating in use. One example of one or more internal rails 48 positioned on an internal surface of the pump body is shown in FIG. 7. The piston 26 may be provided with one or more protrusions that slide within the rails 48. Alternatively, the rails may be provided as an elongated protrusion on the pump body, and the piston may have one or more grooves that receive the elongated protrusion in use.

The movement of the piston(s) 26, 34 may be controlled by differential pressure. For example, most passenger aircraft and other passenger transport vehicles have a vacuum disposal system that applies vacuum to transport waste water from toilets and/or sinks into an on-board waste water storage tank. In aircraft, the vacuum is generated either by the pressure differential between the pressurized cabin and the reduced pressure outside of an aircraft at high flight altitudes or by a vacuum generator at ground level or at low flight altitudes. The pressure differential created by either system can be used to force the piston 26 to contract and to pull water into the space created by such movement.

In use, the interior of two normally-extended pistons 26, 34 may be exposed to vacuum. It is possible for each piston to be exposed independently to the same vacuum source or for them to be connected to separate vacuum sources. In any event, exposure to vacuum allows atmospheric pressure to push the pistons 26, 23 back into the yokes/cylinder barrels 50, into a contracted state. In this position, the spring 28 on each piston 26, 34 may be compressed and stores the potential energy provided by the differential pressure gradient. It is with this potential energy that fluids can be pumped. In other embodiments, the pistons may be moved via vacuum alone, via hydraulic pressure, or via magnetic force. In one example, the pressure differential/vacuum may be applied to the pump body 12 via at least one vacuum inlet 36. The at least one vacuum inlet 36 may deliver a vacuum created by an on-board vacuum generator or vacuum created by the difference in pressures between the aircraft cabin and the outside atmosphere. FIG. 1 shows an embodiment that uses two vacuum inlets 36, 38 controlled by a vacuum control member 40. It should be understood, however, that only one vacuum inlet need be provided (as shown in FIGS. 4 and 5) or that more than two vacuum inlets may be provided. As shown in FIG. 4, an application of differential pressure to the pump body 12 can force the piston 26 to contract. This contraction creates spaces and vacuum for the entry of fluid into the at least one fluid inlet 22. The inlets described herein may be operated by valves, such as pinch valves, solenoid valves, or any other appropriate valve that can control the flow of fluids (either liquid or gases).

A control member 40 may also be provided as a part of the pump system 10. Control member 40 may be controlled by a vent valve (C), which may toggle between venting the system via a vent channel 44 or allowing vacuum to be applied to the system via a vacuum channel 46. Control member 40 can cause the removal of the vacuum from the pump body, creating a pressure gradient, which can force the piston(s) 26, 34 to expand, pushing the fluid contained in the reservoir 18 out through the outlet 20. An example of vent being applied to the pump body 12 to create a flush state is shown in FIG. 5. In this Figure, the pistons have expanded into the reservoir, which forces the fluid contained in the reservoir out as a high force/pressure/velocity.

Referring now more specifically to FIG. 4, the function of the various valves (a, b, and c) that coordinate flow of fluid is described. The below description is for use of the pump to receive grey water and to deliver the grey water to a toilet for a flush sequence, but it should be understood that other uses are possible and within the scope of this disclosure. When a vacuum is applied to the pump body 12, the inlet valve (a) is open, allowing grey water/fluid to enter the reservoir 18. (This entry may be via gravity, via pull from pressure, or via external pump, or any other appropriate method.) The outlet valve (b) is closed. The vent/vacuum valve (c) is opened to vacuum and closed to vent. (This valve (c) may be a 3-way valve or any other appropriate form of valve.) The pistons 26, 34 are compressed.

Entry of grey water into the reservoir 18 allows the downward passage of fluid, while preventing the upward backflow. Once a flush request is sent from the toilet to the pump system 10, the following actions may occur to initiate the “pump state” shown in FIG. 5: the inlet valve (a) will close, the outlet valve (b) will open, the vent/vacuum valve (c) will open the vent channel 44 and close the vacuum channel 46. These actions may cause the pistons 26, 34 to expand, pumping the grey water/fluid out of the reservoir 18 through valve (b) and out the outlet 20.

Once the pistons are fully expanded, the following actions may occur to revert back to the “normal state” shown in FIG. 4: the inlet valve (a) will open, the outlet valve (b) will close, the vent/vacuum valve (c) will close the vent channel 44 and open the vacuum channel 46. These actions will cause the pistons 26, 34 to compress, preparing the reservoir 18 for another cycle of refill with grey water. The valves used in this system may be any appropriate form of valve. It has been found that solenoid valves may be particularly useful.

When fully extended, the pistons 26, 34 may be designed to occupy a significant majority of the available volume of the pump reservoir 18. The reservoir 18 shape may be optimized, depending upon the application of the pump system, such that the required pressure and volume of fluid can be delivered via the pumping action of the pistons. Further, piston action can operate in a single-stroke or multi-stroke fashion, delivering a bolus of pumped fluid or a pulsed stream.

In a single-stroke configuration, the full volume of the pump reservoir may be expelled during extension of the piston(s). The pressure of the pumped fluid may change in proportion to the available tension in the spring. As the spring returns to its uncompressed state (e.g., at the end of the stroke), the pressure of the fluid may be found to diminish. In this manner, fluid would generally be pumped as a discrete bolus, with a high initial pressure that diminishes over the course of the stroke.

In a multi-stroke configuration, the reservoir volume may only be reduced by a fraction during each piston stroke, allowing the fluid to be pumped at a generally high pressure, due to conservation of tension within the piston spring. Because each stroke is physically shorter, the differential pressure can more readily drive the piston recovery, allowing for rapid repetition of strokes. If a two-piston pump configuration is used, as shown in FIGS. 4 and 5, the piston actions may be timed to allow for a fairly smooth, constant flow of fluid as each piston complements the slack left by the decompression of the other piston's spring.

In some embodiments, it is envisioned that the pressure differential pump may use shape-memory alloys to achieve non-diminishing pumping pressures throughout the linear stroke of the piston. For example, the tension-compression element of the piston may comprise a shape memory material. Shape-memory allows, non-limiting examples of which include copper-aluminum-nickel or nickel-titanium, can be utilized such that the energy released during spring decompression can be supplanted by the reversible changes in these shape-memory alloys.

The pump system 10 may feature one or more level sensors, which may be comprised of non-intrusive capacitive sensors, to detect when and whether the reservoir 18 is full. The pump system 10 may also feature one or more controllers that send signals to the vacuum control member 40 to open and close the valves at the inlet and outlet and in order to effect pump activation and movement of the desired fluid.

In an alternate embodiment, rather than relying on spring motion to cause movement of the pistons, the pistons may operate based on vacuum alone. A vacuum may be applied to cause the piston to expand, pushing the fluid out of the reservoir.

In a further embodiment, it is possible to provide a single piston that is operated by pressure differentials across two ends of the pump body. At one end, a first pressure differential causes movement of a piston and pulls water into the reservoir 18. Once the reservoir is full or when the pump is otherwise activated, a second pressure differential that enters at the second end of the pump body 12 can cause opposite movement of the piston and force fluid out of an outlet.

In a further embodiment, the pump system 10 may be activated by hydraulic pressure. For example, as shown in FIG. 6, one or more hydraulic cylinders 42 may be used to move fluid through the pump. The pump body 12 is generally provided with at least one fluid inlet 22, at least one fluid outlet 20, a liquid chamber 52, and an air chamber 54. The fluid inlet 22 and fluid outlet 20 are generally governed by check valves or other features that prevent flow of liquid until the valves are opened. A hydraulic cylinder 42 may be positioned within the liquid chamber 52 and used to force movement of the water that enters the chamber 52 out through the inlet 22. The hydraulic cylinder 42 may be operated by a pressure created by fluid built up in the chamber 52 when the inlet and outlets are closed via valves. The hydraulic cylinder 42 may be operated by compressed gas or any other appropriate manner.

In the example shown in FIG. 6, the hydraulic cylinder 42 may include a piston 56 that moves within the liquid chamber 52. The liquid chamber 52 features an inlet 22 and an outlet 20. The liquid chamber 52 is separated from an air chamber 54. The air chamber 54 has an air inlet 58 and a vacuum inlet 60. (Although these inlets are shown as two separate elements, there may be a single inlet provided, and a control system may control the application of vacuum or vent to the inlet.) In use, when the air chamber 54 is evacuated by application of vacuum, the piston 56 moves to the right in FIG. 6. This pulls liquid into the water inlet 22. (It should be understood that check valves may be positioned at each of the inlets/outlets in order to maintain the desired pressure across the vacuum inlet and the air inlet, as well as to prevent backflow of fluid between the fluid inlet 22 and the fluid outlet 20.)

When air is pushed into (or otherwise allowed to enter) the air chamber 54, this creates a differential pressure that forces the piston 56 to move to the left in FIG. 6, forcing liquid out of the liquid chamber 52. For example, the air inlet 58 may have a valve that can be opened to allow vent air to rush in when the vacuum inlet 60 is closed via its valve. In this way, differential pressure causes movement of the piston, which causes movement of the liquid to be pumped.

The components of the pressure differential pump may constructed of any material that can withstand varied environments and pressures. One non-limiting example includes high-density plastic polymers, such as Ultem or PEEK. There are no heavy electromagnets or bearings required. The strength and low mass benefits of these polymer materials provides a value to passenger transport vehicles, where lightweight components can allow for reduced fuel consumption or additional passenger revenue.

It is envisioned that the disclosed pumps may operate on-board passenger transport vehicles such as watercraft vessels, trains, aircraft, as well as other vehicles. The wide variance in environmental conditions between these applications, such as humidity, temperature, salt exposure, and so forth may guide materials to be selected with possible the extremes in mind.

The fluids pumped by the device could vary widely based on application. In one proposed application, potentially low temperature fluids such as anti-freeze may be dosed and delivered to appropriate system components. In this example, the materials and mechanisms within the pump system 10 can be designed to withstand low temperatures encountered by aircraft at altitude or a train in winter, as well as be compatible to withstand various types of applicable fluids. For example, if the pump system 10 is used to pump potable water, materials with sufficient regulatory certification may be chosen to ensure water quality. For example, if the pump system 10 is used to pump grey water from a sink for delivery to an on-board toilet for use as flushing water, the materials may be chosen such that they can withstand various detergents, bacteria and other microorganisms over a period of time, and may have surfaces treated to withstand or discourage undesired microbial growth. For example, if the pump system 10 is used in medical or pharmaceutical applications, further increasing regulatory requirements may dictate materials and size requirements to be used.

It is understood that the present embodiments described may be modified for the specific application such that the pump fulfills the purpose of using differential pressure as the energy source. Modifications within the scope of this disclosure can include a different number of pistons, different reservoir shapes, check valve placement and quantity variation, and material changes. Changes and modifications, additions and deletions may be made to the structures and methods recited above and shown in the drawings without departing from the scope or spirit of the following claims. 

What is claimed is:
 1. A pump system configured to use differential pressure, comprising: a pump body comprising at least one vacuum/air inlet, at least one fluid inlet, at least one fluid outlet, a reservoir configured for containing a fluid, and a vacuum control member for controlling application of vacuum to the reservoir; at least one piston element housed within the pump body, the at least one piston element configured to move in response to a pressure differential created by application or removal of vacuum to the reservoir through the at least one vacuum/air inlet.
 2. The system of claim 1, wherein the at least one piston is moved via a vacuum created, via a spring, via magnetic force, or any combination thereof.
 3. The system of claim 1, wherein the at least one piston is comprised of one or more shape memory alloys.
 4. The system of claim 1, wherein the at least one piston comprises a hydraulic cylinder.
 5. The system of claim 1, wherein the at least one piston comprises a spring piston under compression when vacuum is applied.
 6. The system of claim 1, wherein the at least one piston is configured to contract upon application of vacuum to the at least one vacuum inlet as fluid is pulled into the reservoir via the at least one fluid inlet.
 7. The system of claim 6, wherein the at least one piston is configured to extend upon removal of vacuum to push the fluid out of the reservoir, through the at least one fluid outlet.
 8. The system of claim 1, wherein the at least one piston comprises a piston head and a piston yoke, and further comprising a sleeve around the piston yoke.
 9. The system of claim 1, further comprising one or more piston seals maintained via a low-friction sleeve.
 10. The system of claim 1, wherein the at least one piston is guided via internal rails.
 11. The system of claim 1, further comprising a first valve at the at least one inlet, a second valve at the at least one outlet, and a third valve at the vacuum control member.
 12. The system of claim 1, wherein the at least one piston comprises two pistons that extend into the reservoir to force fluid out through the outlet.
 13. The system of claim 12, wherein the two pistons are timed for multi-stroke action.
 14. The system of claim 1, wherein the at least one piston is physically isolated from pumped fluids.
 15. The system of claim 1, wherein the pump body is comprised of a high-density plastic polymer.
 16. The system of claim 1, wherein the at least one vacuum/air inlet comprises a first vacuum inlet and a second vent air inlet.
 17. A method of using differential pressure to move fluid through a pump system, comprising: providing a pump body comprising a vacuum inlet, a fluid inlet, an outlet, a vacuum control member, and a reservoir configured for containing a fluid; at least one piston housed within the pump body, the at least one piston configured to move in response to a pressure differential; applying a first pressure to the vacuum inlet to create a first movement of the piston and to cause fluid to enter the reservoir through the at least one fluid inlet; venting the first pressure through the vacuum control member to create a second movement of the at least one piston, forcing fluid out the outlet.
 18. The method of claim 17, wherein the at least one piston comprises a spring, and wherein the first movement comprises compression of the spring, and wherein the second movement comprises expansion of the spring.
 19. The method of claim 17, further comprising a first valve at the inlet, a second valve at the outlet, and a third valve at the vacuum control member, and further comprising causing fluid to enter the reservoir by opening the first valve when the second valve is closed; and opening the third valve to vacuum.
 20. The method of claim 17, further comprising a first valve at the inlet, a second valve at the outlet, and a third valve at the vacuum control member, and further comprising causing fluid to exit the reservoir by closing the first valve when the second valve is opened; and opening the third valve to vent.
 21. The method of claim 17, wherein the at least one tension-compression element comprises two pistons that extend into the reservoir to force fluid out through the outlet. 